Studies of carbohydrate and protein pre-loading suggest that appetite in obese/restrained people is suppressed by protein but not by carbohydrate calories. Other studies suggest that chronic dieting (i.e. restrained eating) rather than obesity per se is the cause of this insensitivity of appetite to nutrient intake. Exploratory studies indicate that having subjects imagine foods of different palatability levels may be useful in studying the effects of dieting and other variables.